Open Architecture Networking

The Internet uses an open architecture networking.
Designers are free to design networks however they want.
All these networks can communcicate over the internet.

Each network is connected to the Internet through a router gateway.

Within national boundaries, networks belonging to a large business or a unversity connect directly to the national backbone,
whereas smaller organisations or individuals connect via an ISP, who are then connected to the backbone

Routers

Routers are special switches that recieve incoming packets of data along one link and send that as an outgoing packet to another link.
Each packet contains the IP of the destination, which is used to find the destination and to choose the right outgoing link.
Each network is connect to the Internet through a router gateway.
A router gateway allows one network to be connected to another so that packets from one network can be translated into a form which is compatible to the next
A gateway is only necessary when the communication channels on either side of it use different link layer protocols.
If the channel uses the same link layer protocol, the machine is just a router.

Gateways

Gateways regulate traffic between two dissimilar networks, while routers regulate traffic between similar networks.
A gateway is only necessary when the communcation channels on either side of it use differernt link layer protocols.
If the channel uses the same link layer, a router is used.

Examples of networks

Label

Expansion

WAN

Wide Area Network

MAN

Metropolitan Area Network

CAN

Campus Area Network

LAN

Local Area Network

WLAN

Wireless Local Area Network

PAN

Personal Area Network

Topologies

Thing

Explaination

Bus

All the computers are connected to the same wire, called the backbone

Ring

All the computers are linked in a ring, and a token is passed around

Star

All the computers are connected to a switch

Mesh

All the computers are connected to each other

Wireless

Uses electromagnetic radiation to transmit via the power of a WLAN

Intranet

The Intranet is a term often used to refer to a private connection of LANs and WANs that belongs to an organisation,
and is only accessed via the members of the organisation.

Internet

Nobody owns the internet. However, people still does regulate it.

The internet society was established in 1992 to oversee and manage network protocols and systems.

Network Protocol

A network protocol is a set of rules that a program folows.
This allows for a standardised format of communication.

These rules define:

How to establish and terminate a communication

The format of the data being transferred

Error checking and correction

Compression

The most common protocol is the TCP/IP protocol.

TCP/IP

The protocols that make TCP/IP define how data is transferred over a network.
Programs use TCP/IP to make up network protocols.

End node verification

TCP/IP is decentralised.

Protocols that use TCP/IP

Thingy

Name

Port

What

SSH

Secure Shell

22

Remote control command prompt

Telnet

Terminal Emulation Link Network

23

Remote control command prompt

POP3

Post Office Protocol Version 3

110, (465)

Emails!

SMTP

Simple Mail Transfer Protocol

143, (993)

Emails!

HTTP

Hypertext Transfer Protocol

80

A protocol which transfers files, such as HTML to be viewed in a web browser.

HTTP2

Hypertext Transfer Protocol Version 2

80

A second version which allows for more simultaneous requests to occur.

HTTPS

Hypertext Transfer Protocol (Secure!)

443

The same as HTTP, but wrapped up in a cozy shell of SSL

FTP

File Transfer Protocol

21

Move files across the internet!

SMB

Server Message Block

Move files across the intranet! Also contains other Mircosoft things.

WebDAV

Web Distributed Authoring and Versioning

80, 443

Move files across the internet! An extension to HTTP

SFTP

Secure File Transfer Protocol

22

Move files across the internet! Uses SSH to securely route files.

CSMA/CD

Carrier-sense Multiple Access (with) Collision Detection

If there is a collision, send a packet after a random time, up to 60 seconds before discarding a packet.

CSMA/CA

Carrier-sense Multiple Access (with) Collision Avoidance

Send a packet after a time period

MAC

A MAC address, or a (Machine Access Code) allows for the TCP/IP to transfer data to the correct computer.
This MAC is hard-coded into the physical network interface card.

Name Servers

Name servers store the mapping information between IP addresses and Domain Names.
This data is stored within a DNS server.

Error Checking

All data transmissions are checked for corruption, and have ACKnowledgements.

Ports

Ports are logical "pipelines" which allow for multiple applications to communicate simultaneously.